Finishing a workpiece is a process for the surface treatment of a workpiece which is also known as “superfinishing” or a “microfinishing process”. In this process, a finishing tool which has an abrasive effect, for example a finishing stone or a finishing band, is pressed against the workpiece surface to be treated. In the process, the workpiece surface to be treated rotates. An oscillating movement is superimposed on this rotation of the workpiece surface to be treated, in which oscillating movement the finishing tool and the workpiece surface to be treated move relative to each other in directions parallel to the axis of rotation.
DE 20 2010 006 480 U1 and EP 0 161 748 A2 describe band finishing devices which comprise pressing elements which in each case press a finishing band against a workpiece surface to be finished at the height of a pressing element.
DE 20 2010 006 480 U1 proposes using rigid or comparatively soft and yielding pressing elements. The use of rigid pressing elements has the advantage that imprecisions in an initial geometry of a workpiece to be treated can be compensated at least in part. However, compensation of this kind is limited by the resilience of the finishing band. The use of soft and yielding pressing elements permits planar contact of the finishing band on the workpiece, but has the disadvantage that the pressing elements can deform significantly, in particular in the region of oil outlet holes of a crankshaft, and lead to too much material removal in this region. The oscillating and rotating movement of the workpiece also produces comparatively significant deformation of a soft pressing element, which makes it more difficult to treat a workpiece in a dimensionally stable manner.
EP 2 212 058 B1 discloses a further band finishing device. In this case, a pressing band is provided which supports the rear side of a finishing band. The pressing band is fastened to two bearings which are arranged so as to be spaced apart such that the pressing band wraps around the workpiece over a partial circumference. Although this permits contact of a finishing band over a large contact area, the available pressing forces are relatively low and are unevenly distributed over the partial circumference.
DE 44 19 366 A1 discloses a finishing machine in which pressure bodies are used which have a cup-shaped pressure body main part which is open towards the workpiece and on which a spring plate is placed.